Speed sensor CEL question

[bwh13]

Looked thru all the posts and didin't see an answer to this question:

If the cruise control and OBC are gone, will the speed signal still get to the DME?

As I understand it the speed signal goes from the sending unit ---> speedo ---> cruise control unit ---> OBC ---> DME

The CEL started coming on intermittantly a few months ago but I thought it was connected to the knock sensor wiring problem I had. Didn't see it at all for 6 months after getting the car running. Have the 88 325i S52 OBD1 with E34 harness with Treehouse adapter.

When I swapped in the 3.07 rear diff the speed sensor CEL came on using the stock E30 sending unit. Checked the plug and couldn't see anything wrong. I swapped in the Z3 sending unit and cleared the CEL. Now the CEL comes on after about 50 miles of driving.

[jrdeamicis]

Depends on year.

The back of the cluster should have the speed signal (which comes in through the cluster first and breaks out to the rest of the shit from there).

I would wire you speed wire to the one of 3 Green single plugs on the back of the cluster. Its all over current protected to there.

[bwh13]

Finally (I hope) figured out the speed signal CEL issue. Hooked up the wire to the cruise control plug coming out of the bottom of the speedo going to the C101 plug pin 14. Don't know why it doesn't go thru the speedo printed circuit board, but it doesn't appear to...

Drove around for an hour and no CEL. I did notice that the idle goes up a little if the car is moving, then drops down once stopped. Never noticed it doing that before, but from what other posters have said, that is normal.